Nozzle for ship{40 s propeller with water ejection along the trailing edge of the nozzle

ABSTRACT

A Kort nozzle surrounding a ship&#39;&#39;s propeller has slots along the inner and outer sides of its trailing edge. Water can be selectively drawn into the inner slots and ejected from the outer slots, or vice versa, to augment the action of the nozzle as an accelerating nozzle or as a decelerating nozzle. Alternatively, water can be drawn in and ejected selectively about the periphery of the nozzle to augment steering.

United States Patent Ousterveld [45] July 11,1972

[$41 NOZZLE FOR SHIPS PROPELLER WITH WATER EJECI'ION ALONG THE TRAILING EDGE OF THE NOZZLE [72] Inventor: Madam Wiletn Cornell W, Bennekom, Netherlands [7 3] Assignee: LIPS N.V.

[22] Filed: May 18, 1970 [21] Appl. No.: 38,077

[30] Foreign Application Priority Date May 19, I969 Great Britain ..25.$03/69 [52] US. Cl. ..60I221, 60/229, [15/12. 114/151, 239/265.25, 239126527 [51 Int. Cl. ..B63ll 11/02, 1363b 25/46 [58] Field olSelnh ..60/22 I 222, 226, 228, 229; 239126525, 265.27; 114/151; 115/12, 35, 42

[56] Relereuees Cited UNITED STATES PATENTS Primary Examiner-flareruce R. Gordon Attorney-Young & Thompson ABSTRACT A Kort nonle surrounding a ship's propeller has slots along the inner and outer sides of its trailing edge. Water can be selectively drawn into the inner slots and ejected from the outer slots, or vice verse, to augment the action of the nonle as an accelerating nozzle or as a decelerating nonle. Alternatively, water can be drawn in and ejected selectively about the periphery of the male to augment steering.

7 STARBOARD PATENTEUJUL 11 m2 3,575,424

SHEET 1 or 4 FLOW ACCELE FLOW DECELE- RATING NOZZLE RATING NOZZLE IN VENTOR M4 el/vus M1 1 EM (0mm 1:

00.3 TE/PVEL 0 BY y (7W ATTORNEYS PATENTEuJuu 1 m2 SHEET 2 OF 4 INVENTOR BY FJM-v ATTORNEYS NOZZLE FOR SHIP'S PROPELLER WITH WA'IER EIECTION ALONG THE TRAILING EDGE OF THE NOZZLE The present invention relates to a Kort noule for a ship's propeller with water ejection along the trailing edge of the nozzle.

By encasing a propeller with a nozzle, the rate of flow in the region of the nozzle propeller compared with an open propeller can be accelerated as well as decelerated, dependent on the shape of the nozzle. By encasing a propeller with an accelerating nozzle in case of high propeller loads, for example in the case of tugs, trawlers, tankers, bulk carriers and coasters, an increase in efficiency can be obtained. The accelerating nozzle makes a positive contribution to the propelling force. Upon applying a decelerating nozzle, a pressure increase in the region of the propeller can be obtained, which in certain cases can suppress propeller cavitation.

It can be shown by tests with propeller males that the characteristics of the system are determined largely by the ratio between the propeller disk surface and the outlet surface of the nozzle. For nozzles with a length-diameter ratio of 0.4 to L (these ratios are normal in practice) there seems to exist a fixed relation between the total load over the propeller and the nozzle and the ratio between propeller disk surface and outlet surface of the nozzle.

Accordingly as the outlet surface of the nozzle increases relatively, the circulation around the nozzle increases, the nozzle makes a greater contribution to the propelling force and the efficiency of the system increases. However, the load of the nozzle is limited by the possibility of structural failure at high loads.

The circulation around the nozzle profile and the rate of flow in the region of the propeller are, as mentioned above, largely determined by the outlet surface of the noule. If it would be possible to make adjustable the outlet surface of the nozzle, for instance by means of valves, such a propeller-nozzle system would be appropriate for a wider range of working conditions. In practice, however, a valve mechanism at the outlet edge of the nozzle is impractical.

Accordingly, it is an object of the present invention to provide a nozzle for a ship's propeller, with water ejection along the trailing edge of the nozzle, which will in a practical way augment the action of either an accelerating nozzle or a decelerating nozzle.

It is another object of the present invention to provide such a nozzle which is useful for steering.

Finally, it is an object of the present invention to provide such a nozzle which will be relatively simple and inexpensive to manufacture, easy to install, operate, maintain and repair, and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIG. I is a diagrammatic cross-sectional view of a ship's propeller having a Kort nozzle of the flow-decelerating type, and showing by the arrows the directions of water flow;

FIG. 2 is a view similar to FIG. 1 but showing an acceleratin g nozzle;

FIG. 3 is a diagram of flow patterns corresponding to the various shapes of nozzle;

FIG. 4 is a rear perspective view, with parts broken away, of a ship provided with a nozzle and propeller according to the present invention;

FIG. 5 is a rear view of a ship's propeller and nozzle according to the present invention, indicating operation in a manner to augment the operation of an accelerating nozzle;

FIG. 6 is a cross-sectional view of the structure in FIG. 5;

FIG. 7 is a view similar to FIG. 5 but showing the structure operated for steering; and

FIG. 8 is a cross-sectional view of the structure shown in FIG. 7.

Referring now to the drawings in greater detail, the structure of the present invention is of the general type in which a ship's propeller l is encircled by a Kort nozzle 2 whose cross section or profile is in the form of a highlitt device, either positive or negative depending on whether a decelerating or an accelerating nozzle is desired. The difference is illustrated by comparison of FIGS. 1 and 2.

Such an assembly is mounted in the conventional position with respect to a ship 3, as seen in FIG. 4. As seen in FIGS. 5 and 6, slots 4 are provided about the principal portion of the periphery of the inner side of the trailing edge of the nozzle 2', while slots 5 are provided about the principal portion of the outer periphery. Slots 4 communicate with one or more annular chambers 6 within the nozzle 2, while slots 5 communicate with one or more annular chambers 7 that are separate from chambers 6. Chambers 6 and 7 in turn communicate with conventional pumping apparatus (not shown) within the vessel through conventional ducts and valving apparatus (not shown so that water can be supplied by the pump under pressure selectively either to chambers 6 or to chambers 7, the pump intake being connected to the other of the chambers 6 and 7. Thus, the pumping equipment sucks water in through on set of slots 4 or 5, and ejects it through the other. When water is sucked in through slots 4 and ejected through slots 5, as in FIGS. 5 and 6, the operation of the device as an accelerating nozzle is augmented; but when the direction of water flow is reversed and water is sucked in through slots 5 and ejected through slots 4, then the operation of the device as a decelerating nozzle is augmented.

It is also possible by selective operation of the valving means to effectuate the FIGS. 7 and 8 operation, in which at least one slot 4 on one side of the nozzle takes in water and at least one slot 4 on the opposite side of the nozzle ejects water; while the reverse is true for the associated slots 5. In this way, a steering function is achieved.

The angle between the direction of flow of the water through the slots 4 and 5 and the nozzle profile should be about 60. The water velocity through the slots 4 and 5 should be about three to live times the intake velocity of the system (ship speed corrected for wake effect).

It will of course be understood that the present invention can be used also to maintain the flow of water in the region of the propeller substantially constant so that the propeller can operate with uniform velocity and full power under varying load conditions and sea conditions, the variation in conditions being accommodated by variations in water flow through the slots 4 and 5.

From a consideration of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Having described by invention, I claim:

1. A noule for surrounding a ship's propeller, said nozzle having a leading edge and a trailing edge defining between them a nozzle profile, there being at least one annular slot about the inner periphery of the trailing edge of the nozzle and at least one annular slot about the outer periphery of the trailing edge of the nozzle, means to move water through said at least one annular slot about the outer periphery of the trailing edge of the nozzle in a direction at an angle to said nozzle profile, and means simultaneously to move water in the opposite direction through said at least one annular slot about the inner periphery of the trailing edge of the nozzle at an angle to the nozzle profile which is opposite to said angle of said outer periphery slot whereby water moves in one direction through said outer periphery slot while simultaneously moving in the opposite direction through said inner periphery slot.

2. A nozzle for surrounding a ship's propeller, means to eject water from the nonle along the trailing edge of the nozzle at an angle to the nozzle profile, said ejecting means comprising at least one annular slot about the trailing edge of the nozzle, there being at least one annular slot about the inner periphery of the trailing edge of the nozzle and at least one annular slot about the outer periphery of the trailing edge of the noule, and means for separately moving water through the inner periphery and outer periphery slots in different directions.

3. A nozzle for surrounding a ship's propeller, means to eject water from the nozzle along the trailing edge of the noz- 0 bers in the nonle each zle at an angle to the male profile, said ejecting means comprising at least one annular slot about the trailing edge of the nozzle, said at least one slot being in the form of a plurality of separate slots disposed in end-to-end relation in a line about a periphery of the trailing edge of the nozzle, and means for separately supplying water to and withdrawing water from said slots.

4. A noule as claimed in claim 3, said supply and withdrawal means comprising a plurality of distribution chamindividual to a said slot.

i i U U 

1. A nozzle for surrounding a ship''s propeller, said nozzle having a leading edge and a trailing edge defining between them a nozzle profile, there being at least one annular slot about the inner periphery of the trailing edge of the nozzle and at least one annular slot about the outer periphery of the trailing edge of the nozzle, means to move water through said at least one annular slot about the outer periphery of the trailing edge of the nozzle in a direction at an angle to said nozzle profile, and means simultaneously to move water in the opposite direction through said at least one annular slot about the inner periphery of the trailing edge of the nozzle at an angle to the nozzle profile which is opposite to said angle of said outer periphery slot whereby water moves in one direction through said outer periphery slot while simultaneously moving in the opposite direction through said inner periphery slot.
 2. A nozzle for surrounding a ship''s propeller, means to eject water from the nozzle along the trailing edge of the nozzle at an angle to the nozzle profile, said ejecting means comprising at least one annular slot about the trailing edge of the nozzle, there being at least one annular slot about the inner periphery of the trailing edge of the nozzle and at least one annular slot about the outer periphery of the trailing edge of the nozzle, and means for separately moving water through the inner periphery and outer periphery slots in different directions.
 3. A nozzle for surrounding a ship''s propeller, means to eject water from the nozzle along the trailing edge of the nozzle at an angle to the nozzle profile, said ejecting means comprising at least one annular slot about the trailing edge of the nozzle, said at least one slot being in the form of a plurality of separate slots disposed in end-to-end relation in a line about a periphery of the trailing edge of the nozzle, and means for separately supplying water to and withdrawing water from said slots.
 4. A nozzle as claimed in claim 3, said supply and withdrawal means comprising a plurality of distribution chambers in the nozzle each individual to a said slot. 